Spatial light modulator unit, illumination optical system, exposure device, and device manufacturing method

ABSTRACT

According to one embodiment, a spatial light modulator unit is used in the illumination optical system for illuminating an illumination target surface with light from a light source and comprises: a spatial light modulator with a plurality of optical elements arrayed in a predetermined plane and controlled individually; a spatial light modulation element which applies spatial light modulation to the incident light from the light source and which makes rays of intensity levels according to positions of the respective optical elements, incident on the plurality of optical elements; and a control unit which individually controls the plurality of optical elements on the basis of information about the intensity levels of the rays incident on the respective optical elements.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of PCT/JP2010/072742claiming the benefit of priority of U.S. Provisional Application No.61/282,170 filed on Dec. 23, 2009, the entire contents of which areincorporated herein by reference.

BACKGROUND

1. Field

One embodiment of the invention relates to a spatial light modulatorunit, an illumination optical system, an exposure device, and a devicemanufacturing method.

2. Description of the Related Art

In a typical exposure device of this kind, a light beam outputted from alight source travels through a fly's eye lens as an optical integratorto form a secondary light source (in general, a predetermined lightintensity distribution on an illumination pupil) as a substantialsurface illuminant consisting of a large number of light sources. In thedescription hereinafter, the light intensity distribution on theillumination pupil will be referred to as “pupil intensitydistribution.” The illumination pupil is defined as a position such thatan illumination target surface becomes a Fourier transform plane of theillumination pupil by action of an optical system between theillumination pupil and the illumination target surface (which is a maskor a wafer in the case of the exposure device).

Rays from the secondary light source are condensed by a condenseroptical system to illuminate the mask with a predetermined patternthereon in a superimposed manner. The light passing through the mask isfocused through a projection optical system on the wafer and the maskpattern is projected and exposed (transferred) onto the wafer. Since thepattern formed on the mask is a highly integrated one, it is essentialto obtain a uniform illuminance distribution on the wafer, in order toaccurately transfer the fine pattern onto the wafer.

There is a conventionally proposed illumination optical system capableof continuously changing the pupil intensity distribution (and theillumination condition eventually) (cf. U.S. Patent ApplicationLaid-Open No. 2009/0116093). The illumination optical system disclosedin U.S. Patent Application Laid-Open No. 2009/0116093 uses a movablemulti-mirror system consisting of a large number of microscopic mirrorelements arranged in an array form and individually driven andcontrolled in their inclination angle and inclination direction, todivide an incident beam into small unit rays by respective reflectingfaces thereof and deflect the small unit rays, whereby the cross sectionof the beam is converted into a desired shape or a desired size, so asto realize a desired pupil intensity distribution.

SUMMARY

According to an embodiment, a spatial light modulator unit used in anillumination optical system for illuminating an illumination targetsurface with light from a light source, comprising:

a spatial light modulator with a plurality of optical elements arrayedin a predetermined plane and controlled individually;

a spatial light modulation element which applies spatial lightmodulation to the light incident from the light source and which makesrays of intensity levels according to positions of the respectiveoptical elements, incident on the plurality of optical elements; and

a control unit which individually controls the plurality of opticalelements on the basis of information about the intensity levels of therays incident on the respective optical elements.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

A general architecture that implements the various features of theinvention will now be described with reference to the drawings. Thedrawings and the associated descriptions are provided to illustrateembodiments of the invention and not to limit the scope of theinvention.

FIG. 1 is an exemplary drawing schematically showing a configuration ofan exposure device according to an embodiment;

FIG. 2 is an exemplary drawing schematically showing an internalconfiguration of a spatial light modulator unit;

FIG. 3 is an exemplary drawing for explaining a configuration and actionof a spatial light modulator in the spatial light modulator unit;

FIG. 4 is an exemplary partial perspective view of the major part of thespatial light modulator;

FIGS. 5A and 5B are exemplary drawings for explaining an action of aspatial light modulator in a configuration of a comparative example;

FIGS. 6A and 6B are exemplary drawings for explaining the action of thespatial light modulator in the configuration of the embodiment;

FIG. 7 is an exemplary drawing schematically showing an internalconfiguration of a spatial light modulator unit according to a firstmodification example;

FIG. 8 is an exemplary drawing schematically showing an internalconfiguration of a spatial light modulator unit according to a secondmodification example;

FIG. 9 is an exemplary flowchart showing manufacturing blocks ofsemiconductor devices; and

FIG. 10 is an exemplary flowchart showing manufacturing blocks of aliquid crystal device such as a liquid crystal display device.

DETAILED DESCRIPTION

Various embodiments will be described hereinafter with reference to theaccompanying drawings.

FIG. 1 is an exemplary drawing schematically showing a configuration ofan exposure device according to an embodiment. FIG. 2 is an exemplarydrawing schematically showing an internal configuration of a spatiallight modulator unit shown in FIG. 1. In FIG. 1, the Z-axis is set alonga direction of a normal to a transfer plane (exposed plane) of a wafer Wbeing a photosensitive substrate, the Y-axis along a direction parallelto the plane of FIG. 1 in the transfer plane of the wafer W, and theX-axis along a direction normal to the plane of FIG. 1 in the transferplane of the wafer W.

With reference to FIG. 1, exposure light (illumination light) issupplied from a light source 1 in the exposure device of the presentembodiment. The light source 1 applicable herein is, for example, an ArFexcimer laser light source to supply light at the wavelength of 193 nm,a KrF excimer laser light source to supply light at the wavelength of248 nm, or the like. The light outputted from the light source 1 travelsthrough a beam delivery unit 2 and a spatial light modulator unit 3 intoa relay optical system 4. The beam delivery unit 2 functions to guidethe incident beam from the light source 1 to the spatial light modulatorunit 3, while converting the beam into an optical beam with a crosssection of an appropriate size and shape, and to actively correctpositional variation and angular variation of the beam incident into thespatial light modulator unit 3.

The spatial light modulator unit 3, as shown in FIG. 2, is provided witha reflection-type diffractive optical element 30 which applies spatiallight modulation to the incident light from the light source 1 and whichoutputs the modulated light, a spatial light modulator 31 arranged in anoptical path between the diffractive optical element 30 and the relayoptical system 4, and a control unit 32 which individually controls aplurality of mirror elements in the spatial light modulator 31 on thebasis of a control signal from a main control system CR. The diffractiveoptical element 30 is arranged so as to be optionally inserted into orretracted from an illumination optical path and so as to be replaceablewith another reflection-type diffractive optical element (not shown)with a different diffraction property.

The spatial light modulator 31, as described below, has a plurality ofmirror elements arrayed in a predetermined plane and controlledindividually, and a driving unit which individually controls and drivespostures of the mirror elements on the basis of a signal from thecontrol unit 32. The control unit 32 controls switching of thediffractive optical elements relative to the illumination optical path,based on a control signal from the main control system CR. The switchingof the diffractive optical elements can be implemented, for example, bya method such as the well-known turret method and slide method. Theaction of the diffractive optical element 30 and the configuration andaction of the spatial light modulator 31 will be described later.

The light outputted from the spatial light modulator unit 3 travelsthrough the relay optical system 4 as a Fourier transform optical systeminto a predetermined plane 5. Namely, the relay optical system 4 is soset that a front focal position thereof is approximately coincident withthe position of the array plane of the mirror elements in the spatiallight modulator 31 and that a rear focal position thereof isapproximately coincident with the position of the predetermined plane 5.As described later, the light having traveled via the spatial lightmodulator 31 variably forms a light intensity distribution according tothe postures of the mirror elements on the predetermined plane 5.

The light forming the light intensity distribution on the predeterminedplane 5 travels through a relay optical system 6 to enter a micro fly'seye lens (or fly's eye lens) 7. The relay optical system 6 sets thepredetermined plane 5 and an entrance plane of the micro fly's eye lens7 in an optically conjugate relation. Therefore, the light havingtraveled via the spatial light modulator unit 3 forms a light intensitydistribution corresponding to the light intensity distribution formed onthe predetermined plane 5, on the entrance plane of the micro fly's eyelens 7 arranged at the position optically conjugate with thepredetermined plane 5.

The micro fly's eye lens 7 is, for example, an optical elementconsisting of a large number of microscopic lenses with a positiverefractive power which are arranged in a matrix in a plane and densely,and is constructed by forming the microscopic lens group by etching on aplane-parallel plate. In the micro fly's eye lens, unlike the fly's eyelens consisting of lens elements isolated from each other, the largenumber of microscopic lenses (microscopic refracting faces) areintegrally formed without being isolated from each other. However, themicro fly's eye lens is an optical integrator of the same wavefrontdivision type as the fly's eye lens in that the lens elements arearranged in a matrix on a plane.

The rectangular microscopic refracting faces as unit wavefront divisionfaces in the micro fly's eye lens 7 have the rectangular shape similarto the shape of an illumination field to be formed on a mask M (andeventually similar to the shape of an exposure region to be formed onthe wafer W). The micro fly's eye lens 7 applicable herein is, forexample, a cylindrical micro fly's eye lens. The configuration andaction of the cylindrical micro fly's eye lens are disclosed, forexample, in U.S. Pat. No. 6,913,373.

The beam incident into the micro fly's eye lens 7 is two-dimensionallydivided by the large number of microscopic lenses and a secondary lightsource with a light intensity distribution approximately identical tothe light intensity distribution formed on the entrance plane (asubstantial surface illuminant consisting of a large number of smalllight sources: pupil intensity distribution) is formed on a rear focalplane of the micro fly's eye lens 7 or on an illumination pupil near it.Rays from the secondary light source formed on the illumination pupilimmediately behind the micro fly's eye lens 7 are incident on anillumination aperture stop (not shown). The illumination aperture stopis arranged at or near the rear focal plane of the micro fly's eye lens7 and has an aperture (light transmitting portion) of the shapecorresponding to the secondary light source.

The illumination aperture stop is configured so as to be optionallyinserted into or retracted from the illumination optical path and so asto be replaceable with any one of aperture stops having respectiveapertures of different sizes and shapes. Switching of the illuminationaperture stops can be implemented, for example, by a method such as thewell-known turret method and slide method. The illumination aperturestop is arranged at the position approximately optically conjugate withan entrance pupil plane of a projection optical system PL describedbelow, and defines the range of contribution of the secondary lightsource to illumination. It is also possible to omit the installation ofthe illumination aperture stop.

The rays from the secondary light source limited by the illuminationaperture stop travel through a condenser optical system 8 to illuminatea mask blind 9 in a superimposed manner. In this way, a rectangularillumination field according to the shape and focal length of therectangular microscopic refracting faces of the micro fly's eye lens 7is formed on the mask blind 9 as an illumination field stop. Rays havingpassed through a rectangular aperture (light transmitting portion) ofthe mask blind 9 are subjected to condensing action of imaging opticalsystem 10 and thereafter illuminate the mask M with a predeterminedpattern thereon in a superimposed manner. Namely, the imaging opticalsystem 10 forms an image of the rectangular aperture of the mask blind 9on the mask M.

The light through the mask M held on a mask stage MS travels through theprojection optical system PL to form an image of the mask pattern on thewafer (photosensitive substrate) W held on a wafer stage WS. In thisway, the pattern of the mask M is sequentially exposed in each ofexposure regions on the wafer W by one-shot exposure or by scanexposure, while two-dimensionally driving and controlling the waferstage WS and therefore two-dimensionally driving and controlling thewafer W in the plane (XY plane) perpendicular to the optical axis AX ofthe projection optical system PL.

The exposure device of the present embodiment is provided with a pupilintensity distribution measuring unit DT which measures a pupilintensity distribution on a pupil plane of the projection optical systemPL on the basis of the light having traveled through the projectionoptical system PL, and the main control system CR which controls thespatial light modulator unit 3 on the basis of the measurement result ofthe pupil intensity distribution measuring unit DT and which generallycontrols the operation of the exposure device. The pupil intensitydistribution measuring unit DT is provided with a CCD imaging unit withan image pickup plane, for example, arranged at the position opticallyconjugate with the pupil position of the projection optical system PL,and monitors pupil intensity distributions about respective points onthe image plane of the projection optical system PL (which are pupilintensity distributions formed at the pupil position of the projectionoptical system PL by rays incident on the respective points). Thedetailed configuration and action of the pupil intensity distributionmeasuring unit DT can be seen, for example, with reference to U.S.Patent Application Laid-Open No. 2008/0030707.

In the present embodiment, the mask M arranged on an illumination targetsurface of the illumination optical system (and, in turn, the wafer W)is illuminated by Köhler illumination, using the secondary light sourceformed by the micro fly's eye lens 7, as a light source. For thisreason, the position where the secondary light source is formed isoptically conjugate with the position of an aperture stop AS of theprojection optical system PL and the plane where the secondary lightsource is formed can be called an illumination pupil plane of theillumination optical system. Typically, the illumination target surface(the plane where the mask M is arranged or the plane where the wafer Wis arranged when the illumination optical system is considered toinclude the projection optical system PL) becomes an optical Fouriertransform plane with respect to the illumination pupil plane. The pupilintensity distribution is a light intensity distribution (luminancedistribution) on the illumination pupil plane of the illuminationoptical system or on a plane optically conjugate with the illuminationpupil plane.

When the number of divisions of the wavefront by the micro fly's eyelens 7 is relatively large, there is a high correlation between theglobal light intensity distribution formed on the entrance plane of themicro fly's eye lens 7 and the global light intensity distribution(pupil intensity distribution) of the entire secondary light source. Forthis reason, the light intensity distributions on the entrance plane ofthe micro fly's eye lens 7 and on planes optically conjugate with theentrance plane can also be called pupil intensity distributions. In theconfiguration of FIG. 1, the relay optical systems 4, 6 and the microfly's eye lens 7 constitute a distribution forming optical system whichforms the pupil intensity distribution on the illumination pupilimmediately behind the micro fly's eye lens 7 on the basis of the rayshaving traveled via the spatial light modulator 31 in the spatial lightmodulator unit 3.

Next, the configuration and action of the spatial light modulator 31 inthe spatial light modulator unit 3 will be specifically described. Thespatial light modulator 31, as shown in FIG. 3, is provided with aplurality of mirror elements 31 a arrayed in a predetermined plane, abase 31 b holding the mirror elements 31 a, and a driving unit 31 cwhich individually controls and drives the postures of the mirrorelements 31 a through a cable (not shown) connected to the base 31 b. Inthe spatial light modulator 31, the postures of the mirror elements 31 aare changed each by action of the driving unit 31 c operating based on acontrol signal output by the control unit 32 in accordance with acommand from the main control system CR, whereby the mirror elements 31a are set in their respective predetermined orientations.

The spatial light modulator 31, as shown in FIG. 4, is provided with aplurality of microscopic mirror elements 31 a arrayed two-dimensionally,and functions to variably apply spatial modulation according to theposition of incidence of incident light, to the incident light andoutput the modulated light. For simplicity of description andillustration, FIGS. 3 and 4 show a configuration example in which thespatial light modulator 31 is provided with 4×4=16 mirror elements 31 a,but in fact the spatial light modulator 31 is provided with much moremirror elements 31 a than the sixteen elements.

With reference to FIG. 3, when a group of rays are incident on thespatial light modulator 31, a ray L1 is incident on the mirror elementSEa out of the plurality of mirror elements 31 a and a ray L2 isincident on the mirror element SEb different from the mirror elementSEa. Similarly, a ray L3 is incident on the mirror element SEc differentfrom the mirror elements SEa, SEb, and a ray L4 is incident on themirror element SEd different from the mirror elements SEa-SEc. Themirror elements SEa-SEd apply respective spatial modulations setaccording to their positions, to the rays L1-L4.

When the spatial light modulator 31 is in a standard state in which thereflecting faces of all the mirror elements 31 a are set along oneplane, the spatial light modulator 31 is configured so that raysincident along the direction parallel to the optical axis AX of theoptical path between the diffractive optical element 30 and the spatiallight modulator 31 travel in directions approximately parallel to theoptical axis AX of the optical path between the spatial light modulator31 and the relay optical system 4, after reflected by the spatial lightmodulator 31. As described above, the array plane of the mirror elements31 a in the spatial light modulator 31 is positioned at or near thefront focal position of the relay optical system 4.

Therefore, the rays with a predetermined angle distribution afterreflected by the mirror elements SEa-SEd in the spatial light modulator31 form predetermined light intensity distributions SP1-SP4 on thepredetermined plane 5 and eventually form light intensity distributionscorresponding to the light intensity distributions SP1-SP4 on theentrance plane of the micro fly's eye lens 7. Namely, the relay opticalsystem 4 converts the angles given to the emerging rays by the mirrorelements SEa-SEd in the spatial light modulator 31, into positions onthe predetermined plane 5 being the far-field region (Fraunhoferdiffraction region) of the spatial light modulator 31. In this manner,the light intensity distribution (pupil intensity distribution) of thesecondary light source formed by the micro fly's eye lens 7 becomes adistribution corresponding to the light intensity distribution formed onthe entrance plane of the micro fly's eye lens 7 by the spatial lightmodulator 31 and the relay optical systems 4, 6.

The spatial light modulator 31, as shown in FIG. 4, is a movablemulti-mirror system including the mirror elements 31 a being the largenumber of microscopic reflecting elements arrayed regularly andtwo-dimensionally along one plane in a state in which the planarreflecting faces are facing up. Each mirror element 31 a is movable andan inclination of the reflecting face thereof, which is an angle and adirection of inclination of the reflecting face, is individuallycontrolled by action of the driving unit 31 c operating based on acontrol signal from the control unit 32. Each mirror element 31 a can berotated continuously or discretely by a desired angle of rotation aroundrotational axes along two directions parallel to the reflecting face andperpendicular to each other. Namely, the inclination of the reflectingface of each mirror element 31 a can be controlled two-dimensionally.

In the case where the reflecting face of each mirror element 31 a isdiscretely rotated, it is preferable to perform control to switch theangle of rotation in a plurality of states (e.g., . . . , −2.5°, −2.0°,. . . 0°, +0.5° . . . +2.5°, . . . ). FIG. 4 shows the mirror elements31 a with the contour of square shape, but the contour of the mirrorelements 31 a does not always have to be limited to the square shape. Interms of light utilization efficiency, however, the contour can be ashape permitting an array to minimize the clearance between the mirrorelements 31 a (i.e., a shape permitting a close-packed structure). Interms of light utilization efficiency, the spacing between two adjacentmirror elements 31 a can be controlled to a necessary minimum value.

In the present embodiment, the spatial light modulator 31 employed is,for example, the spatial light modulator in which the orientations ofthe mirror elements 31 a arrayed two-dimensionally are continuouslychanged. The spatial light modulator of this kind can be selected, forexample, from those disclosed in European Patent Publication No. 779530,U.S. Pat. No. 6,900,915, U.S. Pat. No. 7,095,546, and Japanese PatentApplication Laid-open No. 2006-113437. The orientations of the mirrorelements 31 a arrayed two-dimensionally may be controlled so as to havea plurality of discrete stages.

In the spatial light modulator 31, the postures of the mirror elements31 a are changed each by action of the driving unit 31 c operating inaccordance with a control signal from the control unit 32, whereby themirror elements 31 a are set in their respective predeterminedorientations. The rays reflected at respective predetermined angles bythe mirror elements 31 a of the spatial light modulator 31 form adesired pupil intensity distribution on the illumination pupilimmediately behind the micro fly's eye lens 7. Furthermore, a desiredpupil intensity distribution is also formed at the position of anotherillumination pupil optically conjugate with the illumination pupilimmediately behind the micro fly's eye lens 7, i.e., at the pupilposition of the imaging optical system 10 and at the pupil position ofthe projection optical system PL (the position where the aperture stopAS is arranged).

FIG. 5A is an exemplary drawing showing a state in which pupil intensitydistributions with a plurality of intensity levels are formed on thepredetermined plane 5 being the far-field region (Fraunhofer diffractionregion) of the spatial light modulator 31, in a configuration of acomparative example in which the diffractive optical element 30 isexcluded from between the beam delivery unit 2 and the spatial lightmodulator 31. Rays L1-L4 incident on the mirror elements SEa-SEd in thespatial light modulator 31, as shown in FIG. 5B, have respective uniformintensity distributions throughout their cross section and the intensityI equal to each other.

In this case, as shown in FIG. 5A, the rays L1 and L2 via the mirrorelements SEa and SEb in the spatial light modulator 31 are superimposedin one unit region (divided region) on the pupil intensity distribution,thereby to obtain a light intensity distribution SP1 with an intensitylevel of a multiple of the minimum intensity (which is the intensity ofthe light intensity distribution SP3 or SP4 by the ray L3 or L4 incidentvia one mirror element SEc or SEd to one divided region).

Now, let us consider a situation in the above configuration (theconfiguration without the diffractive optical element 30 between thebeam delivery unit 2 and the spatial light modulator 31) wherein aparallel light beam with a uniform intensity distribution and a squarecross section is incident on the spatial light modulator 31 having fourthousand mirror elements 31 a and wherein a pupil intensity distributionof a circular shape centered on the optical axis AX is formed on theillumination pupil immediately behind the micro fly's eye lens 7. Inthis case, even if the number of divisions of the circular pupilintensity distribution (the number of pixels) is set to 32, intensitylevels (gray levels) in each divided region (each pixel) of the pupilintensity distribution are only about four stages at most, as shown byformula (1) below. In addition, the intensity levels of the respectivedivided regions are integral multiples of the minimum intensity (one,two, or more times the minimum intensity).

4000/(32×32×π/4)≈4.9  (1)

Namely, in the case of the configuration using the spatial lightmodulator of a high durability type with a relatively small number ofmirror elements, it is infeasible to ensure a required degree of freedomfor the intensity levels of the respective divided regions of the pupilintensity distribution unless the number of divisions of the pupilintensity distribution is set smaller or unless the degree of freedomfor the shape of the pupil intensity distribution is sacrificed. Inanother way, intensity levels of multiples of the minimum intensity (theintensity of the ray incident via one mirror element to one dividedregion) cannot be realized unless rays via a plurality of mirrorelements are superimposed on one unit region (divided region) on thepupil intensity distribution; therefore, when the required degree offreedom is ensured for the intensity levels of the pupil intensitydistribution, the number of divisions of the pupil intensitydistribution becomes smaller and the degree of freedom for the shape ofthe pupil intensity distribution is reduced eventually. As aconsequence, it is infeasible to achieve both of a high degree offreedom for the shape of the pupil intensity distribution and a highdegree of freedom for the intensity levels of the pupil intensitydistribution.

In the present embodiment, the reflection type diffractive opticalelement 30 is arranged in the optical path between the beam deliveryunit 2 and the spatial light modulator 31. The diffractive opticalelement 30 functions to apply spatial light modulation to the incidentlight from the light source 1 and to make rays of intensity levelsaccording to positions of the respective mirror elements, incident onthe mirror elements 31 a of the spatial light modulator 31. In a simpleexample, each of rays incident via the diffractive optical element 30onto the respective mirror elements 31 a has a uniform intensitydistribution, and the intensity levels of the rays incident on themirror elements 31 a are discretely distributed. In other words, therays incident via the diffractive optical element 30 onto the spatiallight modulator 31 have a discontinuous intensity distribution acrossthe cross section thereof, typically, an intensity distribution varyingstepwise.

FIG. 6A is an exemplary drawing showing a state in which a pupilintensity distribution with a plurality of intensity levels is formed onthe predetermined plane 5 being the far-field region (Fraunhoferdiffraction region) of the spatial light modulator 31, in theconfiguration of the present embodiment wherein the reflection typediffractive optical element 30 is arranged in the optical path betweenthe beam delivery unit 2 and the spatial light modulator 31. Each of therays L1-L4 incident on the mirror elements 31 a of the spatial lightmodulator 31, as shown in FIG. 6B, has a uniform intensity distributionacross the cross section thereof, but their light intensities I aredifferent from each other. In other words, the rays L1-L4 have aplurality of intensity levels distributed discretely.

As a consequence, even if the rays L1-L4 via the mirror elements SEa-SEdof the spatial light modulator 31 are made incident on mutuallydifferent unit regions (divided regions) on the pupil intensitydistribution, the intensity levels of the rays L1-L4 arriving at therespective divided regions of the pupil intensity distribution formed onthe predetermined plane 5 become values according to the intensitylevels of the rays L1-L4 incident on the corresponding mirror elementsSEa-SEd, as shown in FIG. 6A.

In the present embodiment, as described above, the control unit 32individually controls the plurality of mirror elements 31 a so thatlight via one mirror element 31 a is incident on one divided region(unit region) on the pupil intensity distribution, for example, based oninformation about intensity levels of incident rays to the respectivemirror elements 31 a and information about the pupil intensitydistribution. As a result, the intensity levels of the respectivedivided regions of the pupil intensity distribution become valuesaccording to the intensity levels of the incident rays on thecorresponding mirror elements 31 a and therefore the intensity levels ofthe respective divided regions of the pupil intensity distributionbecome distributed discretely. In addition, ratios of intensity levelsof the respective divided regions to the minimum intensity can be variedin many ways. This means that a high degree of freedom for the intensitylevels of the respective divided regions of the pupil intensitydistribution is ensured even if the number of divisions of the pupilintensity distribution is set equal to the number of mirror elements 31a in the spatial light modulator 31 so as to ensure a high degree offreedom for the shape of the pupil intensity distribution.

As described above, the spatial light modulator unit 3 of the presentembodiment is provided with the diffractive optical element 30 as aspatial light modulation element to apply the spatial light modulationto the incident light from the light source 1 and to make the rays ofintensity levels according to the positions of the respective mirrorelements, incident on the plurality of mirror elements 31 a of thespatial light modulator 31. Therefore, the degree of freedom for theintensity levels of the pupil intensity distribution can be increasedwithout decreasing the degree of freedom for the shape of the pupilintensity distribution, by individually controlling the plurality ofmirror elements 31 a on the basis of the information about the intensitylevels of the rays incident on the respective mirror elements 31 a.Particularly, in the present embodiment, the degree of freedom for theintensity levels of the pupil intensity distribution can be furtherincreased by switching of the diffractive optical elements 30 withdifferent diffraction properties with respect to the illuminationoptical path to change the discrete distribution of intensity levels ofthe rays incident on the mirror elements 31 a.

The illumination optical system (2-10) of the present embodiment is ableto realize highly-diverse illumination conditions, while increasing thedegree of freedom for the intensity levels of the pupil intensitydistribution, without decreasing the degree of freedom for the shape ofthe pupil intensity distribution formed on the illumination pupilimmediately behind the micro fly's eye lens 7, using the spatial lightmodulator unit 3. Furthermore, the exposure device (2-WS) of the presentembodiment is able to perform excellent exposure under an appropriateillumination condition realized according to the property of the patternof the mask M to be transferred, using the illumination optical system(2-10) realizing the highly-diverse illumination conditions.

In the foregoing description, the operational effect of the presentembodiment was described based on the example in which the intensitylevels of the rays incident on the mirror elements 31 a via thediffractive optical element 30 were discretely distributed, i.e., theexample in which the rays incident via the diffractive optical element30 onto the spatial light modulator 31 had the stepwise(discontinuously) varying intensity distribution. However, withouthaving to be limited to this, an operational effect similar to that inthe above embodiment can also be achieved even in the case where therays incident via the diffractive optical element 30 onto the spatiallight modulator 31 have the intensity distribution continuously(smoothly) varying across the cross section thereof, because a rayincident on each mirror element 31 a has an approximately uniformintensity distribution and intensity levels of the rays incident on themirror elements 31 a are almost discretely distributed.

In the above description, the operational effect of the presentembodiment was described based on the simple example in which the lightvia one mirror element 31 a was made incident on one divided region(unit region) on the pupil intensity distribution. However, withouthaving to be limited to this, it is needless to mention that rays via aplurality of mirror elements 31 a may be superimposed on one dividedregion on the pupil intensity distribution as occasion demands.

In the above description, the spatial light modulator capable ofindividually controlling the orientations (angles: inclinations) of thereflecting faces arrayed two-dimensionally is used as a spatial lightmodulator with a plurality of mirror elements arrayed two-dimensionallyand controlled individually. However, without having to be limited tothis, it is also possible, for example, to use a spatial light modulatorcapable of individually controlling heights (positions) of thereflecting faces arrayed two-dimensionally. The spatial light modulatorof this kind to be used can be selected from the spatial lightmodulators disclosed, for example, in U.S. Pat. No. 5,312,513 and inFIG. 1d in U.S. Pat. No. 6,885,493. In these spatial light modulators, atwo-dimensional height distribution is formed whereby incident light issubjected to the same action as that of a diffractive surface. Theaforementioned spatial light modulator with the plurality of reflectingfaces arrayed two-dimensionally may be modified, for example, accordingto the disclosures in U.S. Pat. No. 6,891,655, and in U.S. PatentApplication Laid-Open No. 2005/0095749. corresponding thereto.

In the above embodiment the spatial light modulator 31 is provided withthe plurality of mirror elements 31 a arrayed two-dimensionally in thepredetermined plane, but, without having to be limited to this, it isalso possible to use a transmission type spatial light modulator with aplurality of transmissive optical elements arrayed in a predeterminedplane and controlled individually.

In the above embodiment there is no optical system arranged in theoptical path between the spatial light modulation element 30 and thespatial light modulator 31, but a relay optical system may be arrangedin the optical path between them. This relay optical system may be aFourier transform optical system which forms an optical Fouriertransform plane of the plane where the spatial light modulation element30 is arranged, on the spatial light modulator 31.

In the above embodiment the reflection type diffractive optical element30 is used as a spatial light modulation element which applies spatiallight modulation to the incident light from the light source 1 and whichmakes rays of intensity levels according to positions of the respectiveelements, incident on the mirror elements 31 a. However, it is alsopossible to use a transmission type diffractive optical element, insteadof the reflection type diffractive optical element 30.

It is also possible to adopt a configuration using a reflection typespatial light modulator 33 with a plurality of mirror elements 33 aarrayed in a predetermined plane and controlled individually, instead ofthe reflection type diffractive optical element 30, as shown in FIG. 7.In a spatial light modulator unit 3A according to the first modificationexample of FIG. 7, the spatial light modulator 33 has the plurality ofmirror elements 33 a arrayed two-dimensionally, and a driving unit 33 cto individually control and drive postures of the mirror elements, as inthe case of the spatial light modulator 31. The driving unit 33 ccontinuously or discretely changes orientations of the mirror elements33 a, based on a control signal from the control unit 32. A relayoptical system 34 is arranged in the optical path between the spatiallight modulator 33 and the spatial light modulator 31. This relayoptical system 34 may be a Fourier transform optical system which formsan optical Fourier transform plane of the array plane where theplurality of mirror elements 33 a of the spatial light modulator 33 arearrayed, on the spatial light modulator 31.

In the first modification example, light via one mirror element 33 a inthe spatial light modulator 33 is selectively incident via the relayoptical system 34 onto a set of mirror elements 31 a in the spatiallight modulator 31. As a consequence, intensity levels of rays incidentvia the spatial light modulator 33 and the relay optical system 34 tothe mirror elements 31 a are discretely distributed and the raysincident on the spatial light modulator 31 have an intensitydistribution stepwise varying across the cross section thereof.

In this manner, the postures of the mirror elements 33 a in the spatiallight modulator 33 are individually controlled to vary the discretedistribution of intensity levels of rays incident on the mirror elements31 a in the spatial light modulator 31, whereby it is feasible toachieve both of a high degree of freedom for the shape of the pupilintensity distribution and a high degree of freedom for the intensitylevels of the pupil intensity distribution. In the first modificationexample the spatial light modulator 33 is provided with the mirrorelements 33 a arrayed two-dimensionally, but, without having to belimited to this, it is also possible to use a transmission type spatiallight modulator with a plurality of transmissive optical elementsarrayed in a predetermined plane and controlled individually.

It is also possible to adopt a configuration in which a filter 35 with apredetermined spatial reflectance distribution is used as the spatiallight modulation element, as shown in FIG. 8. In a spatial lightmodulator unit 3B according to the second modification example of FIG.8, the filter 35 is arranged, for example, so as to be optionallyinserted into or retracted from the illumination optical path and so asto be replaceable with another filter with a different reflectancedistribution (not shown). In the second modification example, as in thecase of the aforementioned embodiment, intensity levels of rays incidentvia the filter 35 onto the mirror elements 31 a are also discretelydistributed and the rays incident on the spatial light modulator 31 havean intensity distribution varying stepwise across the cross sectionthereof.

In the second modification example, a plurality of filters 35 withdifferent reflectance distributions may be switched from one to anotherwith respect to the illumination optical path to change the discretedistribution of intensity levels of rays incident on the mirror elements31 a, whereby the degree of freedom for the intensity levels of thepupil intensity distribution can be further increased. The filter 35with the predetermined spatial reflectance distribution is used in thesecond modification example, but, without having to be limited to this,it is also possible to use a filter with a predetermined spatialtransmittance distribution.

Generally, the control method of the present embodiment is to make raysof discrete intensity levels incident on the respective optical elementsof the spatial light modulator arranged in the optical path of theillumination optical system and individually control the opticalelements on the basis of information about the discrete intensitylevels. Furthermore, the control method of the present embodiment may beexecuted by a computer, using a control program to control drives of theoptical elements in the spatial light modulator with the opticalelements arrayed in the predetermined plane and controlled individually.

In the foregoing embodiment, the micro fly's eye lens 7 was used as anoptical integrator, but an optical integrator of an internal reflectiontype (typically, a rod type integrator) may be used instead thereof. Inthis case, a condensing optical system for condensing the light from thepredetermined plane 5 is arranged instead of the relay optical system 6.Then, instead of the micro fly's eye lens 7 and the condenser opticalsystem 8, the rod type integrator is arranged so that an entrance endthereof is positioned at or near the rear focus position of thecondensing optical system for condensing the light from thepredetermined plane 5. At this time, an exit end of the rod typeintegrator is at the position of the mask blind 9. In the use of the rodtype integrator, a position optically conjugate with the position of theaperture stop AS of the projection optical system PL, in the imagingoptical system 10 downstream the rod type integrator can be called anillumination pupil plane. Since a virtual image of the secondary lightsource on the illumination pupil plane is formed at the position of theentrance plane of the rod type integrator, this position and positionsoptically conjugate therewith can also be called illumination pupilplanes. The condensing optical system, the imaging optical system, andthe rod type integrator can be regarded as a distribution formingoptical system.

In the aforementioned embodiment, the mask can be replaced with avariable pattern forming device which forms a predetermined pattern onthe basis of predetermined electronic data. Use of such a variablepattern forming device can minimize influence on synchronizationaccuracy even if the pattern surface is set vertical. The variablepattern forming device applicable herein can be, for example, a DMD(Digital Micromirror Device) including a plurality of reflectiveelements driven based on predetermined electronic data. The exposuredevice with the DMD is disclosed, for example, in Japanese PatentApplication Laid-Open No. 2004-304135, U. S. Patent ApplicationLaid-Open No. 2007/0296936. Besides the reflection type spatial lightmodulators of the non-emission type like the DMD, it is also possible toapply a transmission type spatial light modulator or a self-emissiontype image display device. The teachings of U. S. Patent ApplicationLaid-Open No. 2007/0296936 are incorporated herein by reference.

The exposure device of the foregoing embodiment is manufactured byassembling various sub-systems containing their respective components asset forth in the scope of claims in the present application, so as tomaintain predetermined mechanical accuracy, electrical accuracy, andoptical accuracy. For ensuring these various accuracies, the followingadjustments are carried out before and after the assembling: adjustmentfor achieving the optical accuracy for various optical systems;adjustment for achieving the mechanical accuracy for various mechanicalsystems; adjustment for achieving the electrical accuracy for variouselectrical systems. The assembling blocks from the various sub-systemsinto the exposure device include mechanical connections, wireconnections of electric circuits, pipe connections of pneumaticcircuits, etc. between the various sub-systems. It is needless tomention that there are assembling blocks of the individual sub-systems,before the assembling blocks from the various sub-systems into theexposure device. After completion of the assembling blocks from thevarious sub-systems into the exposure device, overall adjustment iscarried out to ensure various accuracies as the entire exposure device.The manufacture of the exposure device may be performed in a clean roomin which the temperature, cleanliness, etc. are controlled.

The following will describe a device manufacturing method using theexposure device according to the above-described embodiment. FIG. 9 isan exemplary flowchart showing manufacturing blocks of semiconductordevices. As shown in FIG. 9, the manufacturing blocks of semiconductordevices include depositing a metal film on a wafer W to become asubstrate of semiconductor devices (block S40) and applying aphotoresist as a photosensitive material onto the deposited metal film(block S42). The subsequent blocks include transferring a pattern formedon a mask (reticle) M, into each shot area on the wafer W, using theprojection exposure device of the above embodiment (block S44: exposureblock), and developing the wafer W after completion of the transfer,i.e., developing the photoresist on which the pattern is transferred(block S46: development block).

Thereafter, using the resist pattern made on the surface of the wafer Win block S46, as a mask, processing such as etching is carried out onthe surface of the wafer W (block S48: processing block). The resistpattern herein is a photoresist layer in which depressions andprojections are formed in a shape corresponding to the patterntransferred by the projection exposure device of the above embodimentand which the depressions penetrate throughout. Block S48 is to processthe surface of the wafer W through this resist pattern. The processingcarried out in block S48 includes, for example, at least either etchingof the surface of the wafer W or deposition of a metal film or the like.In block S44, the projection exposure device of the above embodimentperforms the transfer of the pattern onto the wafer W coated with thephotoresist, as a photosensitive substrate or plate P.

FIG. 10 is an exemplary flowchart showing manufacturing blocks of aliquid crystal device such as a liquid crystal display device. As shownin FIG. 10, the manufacturing blocks of the liquid crystal deviceinclude sequentially performing a pattern forming block (block S50), acolor filter forming block (block S52), a cell assembly block (blockS54), and a module assembly block (block S56). The pattern forming blockof block S50 is to form predetermined patterns such as a circuit patternand an electrode pattern on a glass substrate coated with a photoresist,as a plate P, using the aforementioned projection exposure device of theabove embodiment. This pattern forming block includes an exposure blockof transferring a pattern to a photoresist layer, using the projectionexposure device of the above embodiment, a development block ofperforming development of the plate P on which the pattern istransferred, i.e., development of the photoresist layer on the glasssubstrate, to form the photoresist layer in the shape corresponding tothe pattern, and a processing block of processing the surface of theglass substrate through the developed photoresist layer.

The color filter forming block of block S52 is to form a color filter inwhich a large number of sets of three dots corresponding to R (Red), G(Green), and B (Blue) are arrayed in a matrix pattern, or in which aplurality of filter sets of three stripes of R, G, and B are arrayed ina horizontal scan direction. The cell assembly block of block S54 is toassemble a liquid crystal panel (liquid crystal cell), using the glasssubstrate on which the predetermined pattern has been formed in blockS50, and the color filter formed in block S52. Specifically, forexample, a liquid crystal is poured into between the glass substrate andthe color filter to form the liquid crystal panel. The module assemblyblock of block S56 is to attach various components such as electriccircuits and backlights for display operation of this liquid crystalpanel, to the liquid crystal panel assembled in block S54.

The present embodiment is not limited just to the application to theexposure devices for manufacture of semiconductor devices, but can alsobe widely applied, for example, to the exposure devices for displaydevices such as the liquid crystal display devices and plasma displaysformed with rectangular glass plates, and to the exposure devices formanufacture of various devices such as imaging devices (CCDs andothers), micro machines, thin film magnetic heads, and DNA chips.Furthermore, the present embodiment is also applicable to the exposureblock (exposure device) for manufacture of masks (photomasks, reticles,etc.) on which mask patterns of various devices are formed, by thephotolithography process.

The above-described embodiment uses the ArF excimer laser light(wavelength: 193 nm) or the KrF excimer laser light (wavelength: 248 nm)as the exposure light, but, without having to be limited to this, thepresent embodiment can also be applied to any other appropriate laserlight source, e.g., an F2 laser light source which supplies laser lightat the wavelength of 157 nm.

In the foregoing embodiment, it is also possible to apply a technique offilling the interior of the optical path between the projection opticalsystem and the photosensitive substrate with a medium having therefractive index larger than 1.1 (typically, a liquid), which is socalled a liquid immersion method. In this case, it is possible to adoptone of the following techniques as a technique of filling the interiorof the optical path between the projection optical system and thephotosensitive substrate with the liquid: the technique of locallyfilling the optical path with the liquid as disclosed in InternationalPublication WO99/49504; the technique of moving a stage holding thesubstrate to be exposed, in a liquid bath as disclosed in JapanesePatent Application Laid-Open No. 6-124873; the technique of forming aliquid bath of a predetermined depth on a stage and holding thesubstrate therein as disclosed in Japanese Patent Application Laid-OpenNo. 10-303114, and so on. The teachings of International PublicationWO99/49504, Japanese Patent Application Laid-Open No. 6-124873, andJapanese Patent Application Laid-Open No. 10-303114 are incorporatedherein by reference.

The foregoing embodiment was the application of the present embodimentto the illumination optical system for illuminating the mask (or thewafer) in the exposure device, but, without having to be limited tothis, the present embodiment can also be applied to general illuminationoptical systems for illuminating an illumination target surface exceptfor the mask (or the wafer).

It will be understood by those skilled in the art that aspects ofembodiments of the subject matter disclosed above are intended tosatisfy the requirement of disclosing at least one enabling embodimentof the subject matter of each claim and to be one or more such exemplaryembodiments only and to not to limit the scope of any of the claims inany way and particularly not to a specific disclosed embodiment alone.Many changes and modification can be made to the disclosed aspects ofembodiments of the disclosed subject matter of the claims that will beunderstood and appreciated by those skilled in the art, particularly inregard to interpretation of the claims for purposes of the doctrine ofequivalents. The appended claims are intended in scope and meaning tocover not only the disclosed aspects of embodiments of the claimedsubject matter but also such equivalents and other modifications andchanges that would be apparent to those skilled in the art. In additionsto changes and modifications to the disclosed and claimed aspects of thesubject matter disclosed of the disclosed subject matter(s) noted above,others could be implemented.

While the particular aspects of embodiment(s) of the {TITLE} describedand illustrated in this patent application in the detail required tosatisfy 35 U.S.C. §112 is fully capable of attaining any above-describedpurposes for, problems to be solved by or any other reasons for orobjects of the aspects of an embodiment(s) above described, it is to beunderstood by those skilled in the art that it is the presentlydescribed aspects of the described embodiment(s) of the subject matterclaimed are merely exemplary, illustrative and representative of thesubject matter which is broadly contemplated by the claimed subjectmatter. The scope of the presently described and claimed aspects ofembodiments fully encompasses other embodiments which may now be or maybecome obvious to those skilled in the art based on the teachings of theSpecification. The scope of the present {TITLE} is solely and completelylimited by only the appended claims and nothing beyond the recitationsof the appended claims. Reference to an element in such claims in thesingular is not intended to mean nor shall it mean in interpreting suchclaim element “one and only one” unless explicitly so stated, but rather“one or more”. All structural and functional equivalents to any of theelements of the above-described aspects of an embodiment(s) that areknown or later come to be known to those of ordinary skill in the artare expressly incorporated herein by reference and are intended to beencompassed by the present claims. Any term used in the Specificationand/or in the claims and expressly given a meaning in the Specificationand/or claims in the present application shall have that meaning,regardless of any dictionary or other commonly used meaning for such aterm. It is not intended or necessary for a device or method discussedin the Specification as any aspect of an embodiment to address each andevery problem sought to be solved by the aspects of embodimentsdisclosed in this application, for it to be encompassed by the presentclaims. No element, component, or method step in the present disclosureis intended to be dedicated to the public regardless of whether theelement, component, or method step is explicitly recited in the claims.No claim element in the appended claims is to be construed under theprovisions of 35 U.S.C. §112, sixth paragraph, unless the element isexpressly recited using the phrase “means for” or, in the case of amethod claim, the element is recited as a “step” instead of an “act.”

It will be understood also be those skilled in the art that, infulfillment of the patent statutes of the United States, Applicant(s)has disclosed at least one enabling and working embodiment of eachinvention recited in any respective claim appended to the Specificationin the present application and perhaps in some cases only one. Forpurposes of cutting down on patent application length and drafting timeand making the present patent application more readable to theinventor(s) and others, Applicant(s) has used from time to time orthroughout the present application definitive verbs (e.g., “is”, “are”,“does”, “has”, “includes” or the like) and/or other definitive verbs(e.g., “produces,” “causes” “samples,” “reads,” “signals” or the like)and/or gerunds (e.g., “producing,” “using,” “taking,” “keeping,”“making,” “determining,” “measuring,” “calculating” or the like), indefining an aspect/feature/element of, an action of or functionality of,and/or describing any other definition of an aspect/feature/element ofan embodiment of the subject matter being disclosed. Wherever any suchdefinitive word or phrase or the like is used to describe anaspect/feature/element of any of the one or more embodiments disclosedherein, i.e., any feature, element, system, sub-system, component,sub-component, process or algorithm step, particular material, or thelike, it should be read, for purposes of interpreting the scope of thesubject matter of what applicant(s) has invented, and claimed, to bepreceded by one or more, or all, of the following limiting phrases, “byway of example,” “for example,” “as an example,” “illustratively only,”“by way of illustration only,” etc., and/or to include any one or more,or all, of the phrases “may be,” “can be”, “might be,” “could be” andthe like. All such features, elements, steps, materials and the likeshould be considered to be described only as a possible aspect of theone or more disclosed embodiments and not as the sole possibleimplementation of any one or more aspects/features/elements of anyembodiments and/or the sole possible embodiment of the subject matter ofwhat is claimed, even if, in fulfillment of the requirements of thepatent statutes, Applicant(s) has disclosed only a single enablingexample of any such aspect/feature/element of an embodiment or of anyembodiment of the subject matter of what is claimed. Unless expresslyand specifically so stated in the present application or the prosecutionof this application, that Applicant(s) believes that a particularaspect/feature/element of any disclosed embodiment or any particulardisclosed embodiment of the subject matter of what is claimed, amountsto the one an only way to implement the subject matter of what isclaimed or any aspect/feature/element recited in any such claim,Applicant(s) does not intend that any description of any disclosedaspect/feature/element of any disclosed embodiment of the subject matterof what is claimed in the present patent application or the entireembodiment shall be interpreted to be such one and only way to implementthe subject matter of what is claimed or any aspect/feature/elementthereof, and to thus limit any claim which is broad enough to cover anysuch disclosed implementation along with other possible implementationsof the subject matter of what is claimed, to such disclosedaspect/feature/element of such disclosed embodiment or such disclosedembodiment. Applicant(s) specifically, expressly and unequivocallyintends that any claim that has depending from it a dependent claim withany further detail of any aspect/feature/element, step, or the like ofthe subject matter of what is claimed recited in the parent claim orclaims from which it directly or indirectly depends, shall beinterpreted to mean that the recitation in the parent claim(s) was broadenough to cover the further detail in the dependent claim along withother implementations and that the further detail was not the only wayto implement the aspect/feature/element claimed in any such parentclaim(s), and thus be limited to the further detail of any suchaspect/feature/element recited in any such dependent claim to in any waylimit the scope of the broader aspect/feature/element of any such parentclaim, including by incorporating the further detail of the dependentclaim into the parent claim.

1. A spatial light modulator unit used in an illumination optical systemfor illuminating an illumination target surface with light from a lightsource, comprising: a spatial light modulator with a plurality ofoptical elements arrayed in a predetermined plane and controlledindividually; a spatial light modulation element which applies spatiallight modulation to the light incident from the light source and whichmakes rays of intensity levels according to positions of the respectiveoptical elements, incident on the plurality of optical elements; and acontrol unit which individually controls the plurality of opticalelements on the basis of information about the intensity levels of therays incident on the respective optical elements. 2-21. (canceled)